When do I use CAMPUS (previously LTU4) and when do I use "the other one"?

When you are logging in to the computer (the machine as booted up, and you get the CTRL-ALT-DEL prompt, you have a choice on your Username/Password/Domain.

If the Domain is CAMPUS (before LTU4), then you use your standard username (initials/student number) and your network password :
          Username : s_schneider
          Password : ************
          Domain : CAMPUS

If you need to use "the other one" (it will be LTUN and then some numbers .. and it will say "(this computer)" after it, then you use administrator as your username (and there is no password initially - leave it blank) :
          Username : administrator
          Password :     (leave blank for the first time)
          Domain : LTUL0497 (this computer)

Q: Which one should I normally use?    A: CAMPUS! (even at home!)
Basically, you almost never need to use "the other one" ... under rare circumstances (such as adding hardware to the machine), you might have to use it, but I would try to use the CAMPUS (LTU4) account all the time if possible (even when home or not connecting to the network). The reason is that all your settings will be available if you use the same account each time. To paraphrase Patrick Swayze in "Road House" : Use CAMPUS, until it is time to not use CAMPUS!"